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6.
Two body Motion and Conic Assumptions  The motion of a body is governed by attraction due to a single central body.  The mass of the body is negligible compared to that of the central body  The bodies are spherically symmetric with the masses concentrated at the center.  No forces act on the bodies except for gravitational and centrifugal forces acting along the line of centers If these assumptions hold, it can be shown that conic sections are the only possible paths for orbiting bodies and that the central body must be at a focus of the conic Fundamental equations of motion that describe two-body motion under the assumptions Relative Form where G ( m1 m2 ) Closed form Solution 2 p a (1 e ) - Conic Equation r 1 e cos 1 e cos

8.
Representation of a point (spacecraft / body) in motion Position and velocity vectors represent a point in motion in space uniquely Z Satellite perigee 0Vernal i Equatorequinox Node a semi major axis ; e Eccentricity i Inclination ; Right ascension of ascending node Argument of perigee; True anomaly True anomaly

10.
Ephemeris Generation Given full characteristics of spacecraft in a conic at time t1 - either state vector (both position and velocity vectors together) or orbital elements Find the characteristics of the spacecraft in the conic at time t2   r , V at t2   r , V at t 1

17.
Conclusion:Based on the two body model ephemeris generation was carried out.Even though the % error is of the order of 10-1 -10-2 , , their value in absolute is very highThis stress the fact that we need to have a detailed model and do the calculation usingthem, even though carrying them out is very tedious and takes a lot of time.Precision takes precedence over time!